1. Field of the Invention
The present invention relates to a method and apparatus for exchanging roving bobbins in a ring spinning frame, and more particularly relates to an improved method and apparatus for exchanging roving bobbins in a ring spinning frame during a continuous spinning operation thereof.
2. Description of the Related Art
When roving bobbins which are supplying rovings to draft parts of a ring spinning frame become almost exhausted, such almost exhausted roving bobbins, which are supported by the bobbin hangers arranged in the ring spinning frame, should be exchanged with full packaged roving bobbins, to enable a continuous spinning operation of the ring spinning frame. Recently, however, there is a tendency for the roving bobbin exchange operation to be carried out by using an automatic roving bobbin exchange apparatus, because of the difficulty in handling large packaged roving bobbins, which weigh as much as three kgs. Accordingly, several types of automatic apparatuses for exchanging the roving bobbins have been introduced in the spinning industries of many countries.
One such automatic apparatus for carrying out the roving bobbin exchange operation is disclosed in Japanese Unexamined Patent Publication No. 62-53425. This prior art document disclosed that, when the roving bobbins supported by a front row of bobbin hangers in a ring spinning frame become almost exhausted, each of these almost exhausted roving bobbins is exchanged with a corresponding full packaged roving bobbin prepared at a standby position on a supplemental rail arranged along and in front of the ring spinning frame, and the full packaged roving bobbins supported by the corresponding front row of bobbin hangers are exchanged with the corresponding almost half exhausted roving bobbins supported by a back row of bobbin hangers in the ring spinning frame, by using an automatic roving bobbin exchange apparatus.
Japanese Unexamined Patent Publication No. 2-127368 also discloses an apparatus for carrying out an automatic roving bobbin exchange method to be applied to a ring spinning frame, wherein a tapered arrangement of roving bobbins is applied as described hereafter. Namely, at the start of the spinning operation, two types of roving bobbins, i.e., an almost half exhausted roving bobbin, and a full packaged roving bobbin, are alternately supported by a front and back row of bobbin hangers in the ring spinning frame. In the roving bobbin exchange operation, a pair of almost exhausted roving bobbins, one of which is a roving bobbin supported by a bobbin hanger of the front row and the other is a roving bobbin supported by a bobbin hanger of the back row and facing the bobbin hanger of the front row, are exchanged with a pair of fully packaged roving bobbins supported by two adjacent bobbin hangers of a bobbin carriage prepared on a supplemental bobbin rail arranged along and in front of the ring spinning frame. The automatic roving bobbin exchange operation is carried out successively along the ring spinning frame until the roving bobbin exchange operation of all of the almost exhausted roving bobbins of one side of the ring spinning frame is completed. Therefore, in this automatic apparatus for carrying out the roving bobbin exchange method, it is essential to arrange a device for transferring almost exhausted roving bobbins and having a pair of pegs and a device for transferring full package roving bobbins and also having a pair of pegs in parallel on a body of the roving bobbin exchange apparatus, wherein the pitch between the row of the pegs of the transfer device for the almost exhausted roving bobbins and the row of the pegs of the transfer device for the full packaged roving bobbins is equal to the pitch of bobbin hangers of the front and back rows in the ring spinning frame, and accordingly, it is necessary to provide a space in which the above-mentioned two devices may be arranged in the lengthwise direction of the ring spinning frame. This space corresponds to the space for four bobbin hangers, i.e., two adjacent bobbin hangers of the front row and two adjacent bobbin hangers of the back row facing the two bobbin hangers of the front row. Japanese Unexamined Patent Publication No. 2-127368 also discloses an automatic roving bobbin exchange apparatus in which the above-mentioned invention is modified by combining a roving piecing device therewith.
In the first-mentioned prior art, since the roving bobbin exchange operation is simultaneously applied to two or more roving bobbins, the time needed for completing the roving bobbin exchange operation can be remarkably reduced in comparison with that of the second mentioned prior art. Nevertheless the application of the first mentioned prior art is limited to only a ring spinning frame provided with an apparatus for exchanging a roving bobbin and carrying out such an exchange between the bobbin hanger of the front row and a roving bobbin hanger of the back row facing the above-mentioned bobbin hanger of the front row. The second mentioned prior art has an advantage of being able to be applied to a ring spinning frame without the need for the above-mentioned roving bobbin exchange apparatus, which is essential to the first mentioned prior art, but the time needed for completing the roving bobbin exchange operation is much longer, in comparison with that of the first mentioned prior art, because of the transfer of two almost exhausted roving bobbins and of two full packaged roving bobbins. Therefore, for the above-mentioned reasons, the roving bobbin exchange operations based upon the first and second mentioned prior arts are not satisfactory.
To eliminate the above-mentioned problems, in the above-mentioned second invention, for example, an improvement such that a plurality of sets of a unit combination of the almost empty roving bobbin exchange device and the full package roving bobbin exchange device are mounted on the automatic roving bobbin exchange apparatus, to thereby simultaneously carry out the roving bobbin exchange operation for a plurality of sets of almost exhausted roving bobbins could. Here, each set of almost exhausted roving bobbins would consist of an almost exhausted roving bobbin supported by a bobbin hanger of the front row and an almost exhausted roving bobbin supported by a bobbin hanger of the back row facing the bobbin hanger of the front row, with the respective full packaged roving bobbins supported by the corresponding bobbin hangers of the bobbin carriage supported by the supplemental rail. Such a modification of the second mentioned invention is not practical, however because of the resulting mechanical complications of the constituent machine elements and interferences occurring due to the motions of these machine elements.